BY J W. DICKERSON.
PRODUCING mines of the Cripple Creek District in large numbers are now dependent on electric power transmitted from the Colorado Electric Power company's generating plant at Canon City, and the superiority of this method of operating the properties has been amply demonstrated.
This fact was shown in a striking manner a few weeks ago, when many of the steam hoists were shut down, throwing the men out of work, because it was impossible to haul coal up the steep and snow-blockaded roads.
At the same time not a particle of difficulty was experienced in furnishing to the mines connected with the power station an uninterrupted supply of power which was transmitted electrically.
Ever since the completion of the installation the absolute reliability of electric power has been abundantly proved; indeed, had there been the slightest question on that score, the system would have been a woeful failure instead of the splendid success it has proved.
As one of the old miners put it to the writer, ''If I find the hoist is not in shape I am going to get out of that mine mighty quick," and he emphasized his intention by introducing a common expletive. "When you are going to make a shot you want to know just how you are going to get out, and if there is any trouble with the hoist you are in a fix. That's no place for a man to work who values his life."
The Colorado Electric Power company has shown to the miners that no fear of the probability of the failure of the power at a critical juncture is to be dreaded. "It's as sure as the sun," one of the men put it.
The generating plant from which the power for the Cripple Creek District is derived, one of the finest in the United States, is located in the cheap coal region, at the south end of the main business street of Canon City, opposite the Colorado State Penitentiary, and at a point where it may lie readily reached on side tracks by the two excellent railroads entering the place, the Atchison, Topeka and Santa Fe and the Denver and Rio Grande.
Both roads, it may be remarked incidentally, have been at the head among the potent factors that have made Cripple Creek the most wonderful mining district in the country.
Coal for the plant may be brought by side track or by an easy wagon haul from the neighboring mines owned by the company.
The steel and brick power station shown represents the plant as it stands to-day, but the plans of the company provide that eventually the building and the equipment shall be just double in size and capacity those of the present structure.
The boiler room, Fig. 2, contains a battery of Heine water tube boilers supplied by the Heine Safety Boiler company of St. Louis. Water for condensing purposes is taken from the Arkansas River, running 400 feet away from the station.
The surface condensers, Fig. 3, have combined air and circulating pumps manufactured by the Snow Steam Pump Works of Buffalo, N.Y. The feed pumps were manufactured by the same company.
The corrugated tube heaters are of the Wainwright type supplied by the Taunton Locomotive Manufacturing company of Taunton, Mass.
Following out the plan for the entire system the company has made arrangement that one unit in the boilers, pumps and condensers shall always be held in reserve for an emergency.
ENGINES AND DYNAMOS.
There are five engines in the engine room, three for the generators and two for the exciters. The large engines are of the Hamilton-Corliss cross-compound condensing type, having receiver and reheating coils. They were manufactured by the Hooven, Owens and Rentschler company of Hamilton, Ohio.
They are shown in Fig. 4.
Steam is taken at 140 pounds and the speed is 100 revolutions per minute. The exciter engines are the Westinghouse vertical standard type and are run at 350 revolutions per minute. Each of the three large engines is coupled directly to a three-phase Westinghouse 470 kilowatt generator giving current of 3,600 alternations per minute and 30 cycles per second at 500 volts.
These are shown in Figs. 5 and 6.
The two exciting generators are directly connected to their engines by spring couplings. They deliver current at 140 volts, and either of the two exciter units has a capacity to furnish sufficient current for the three generators.
Only two of the generating units are operated at the same time, the third being held in reserve.
Each unit has its own switchboard panel. Fig. 7, to which the current from the generators is conducted by cables under the floor.
Besides the three generator panels a load panel is provided. In addition each generator panel has three ammeters, one for the lead of each generator, and two Shallenberger wattmeters.
A steam gauge, a vacuum gauge and a recording pressure gauge are mounted on a mahogany panel close to the switchboard.
The 500 volt current is conducted by cables along the wall to the room in which are located the step-up transformers, shown in Fig. 8, where the potential is converted from 500 to 20.000 volts for transmission to the Cripple Creek and Victor Districts.
The current from the 20,000 volt terminals of the step-up transformers is conducted to high potential circuit-breakers and thence to the high potential bus bars, both of which are out of reach overhead.
A bank of Wurts non-arcing lightning arresters protects the station from lightning. For purposes of safety all the low potential mains and switches are arranged on one side of the building, while the high potential devices are kept on the other side, overhead and out of reach.
The pole line extends up the mountains, carrying current at 20,000 volts to the center of the Cripple Creek mining district at Dyer where Station Number 1 is located and the headquarters of W. B. Jackson, general superintendent, have been established, Fig. 9.
A good idea of the pole line construction can be gained from Figs. 10 and 11. There are three power wires, two of which are carried at the extremities of a cross arm and one at the top of the poles which are of white cedar and 30 feet in height.
The two wires of a telephone circuit are carried on brackets below the cross arm, as shown in Fig. 10. Inasmuch as the triangle formed by the three power wires is not absolutely equilateral, the wires are transposed three times in the length of the line, as shown in Fig. 10.
The telephone wires are transposed every quarter of a mile.
For lightning protection Wurts arresters are attached at four different points on the line.
The pole line is a little over 24 miles in length. It extends almost in a straight line from Canon City to the Cripple Creek District. At one point an observer can stand on a mountain peak and for ten miles the poles are in so straight a line that the eye cannot detect any departure.
Fig. 11 illustrates this line.
On reaching Station Number 1, shown in Fig. 9, the current goes to a bank of transformers similar to those represented in Fig. 8. Here the action of the transformers is just the reverse of those at the generating station.
The pressure is reduced from 20,000 to 500 volts, and at the latter potential the current is transmitted to the mines and mills in the nearby district, where it is utilized at 450 volts.
Station Number 2 is located at Fairview on the line of the Cripple Creek District electric railway at a distance of one and one-half miles from Station Number 1.
This structure is similar in construction and design to the latter station. Here is arranged a bank of transformers similar to that located in the other substation. The two stations are run in parallel and wherever possible different circuits are interconnected.
At Station No. 1 the 500 volt current is boosted by transformers to 2,500 volts in order to supply mills at some distance including the well-known Arequa and Economic mills.
Recently 6,600 volt transformers were installed for providing current for operating the Cripple Creek District railway by means of rotary converters.
The output of the generating station at the present time averages 400 kilowatts, running up at times to 400 kilowatts. The line loss varies from 5 to 10 per cent, differing with the changing load.
(The second article upon the use of electricity in the Cripple Creek district will appear in the August issue, and will describe the use of electrical apparatus in mines. A large number of views of hoisting plants in the principal mines of the district will be presented.)